1. Field of the Invention
The present invention relates to a semiconductor device and to a method for manufacturing semiconductor devices that reduces the size of semiconductor devices and improves the yield.
2. Prior Art
One type of semiconductor device assembly method is a tape carrier method. Essentially, in this assembly method, as seen from FIG. 7, numerous leads 76 consisting of a conductive layer are formed on the upper surface of a carrier film 2 that is made of a band-form heat-resistant resin film. Then, these leads 76 are bonded to bumps that are surface electrodes of semiconductor chips 78. In addition, these elements are sealed with a resin.
More specifically, in this tape carrier method, the tip ends of the leads 76 formed on the surface of the carrier film 2, as seen from FIG. 8, overhang from windows 2a of the carrier film 2, and the semiconductor chip 78 is caused to approach the leads 76 from below. Then, the leads 76 and bumps 80 are thermally fused while being heated and pressed from above by a bonding tool that has a heater, thus bonding the leads 76 and bumps 80. Bonding of the leads 76 and bumps 80 can be done by another way. A molten resin material in which a conductive powder is dispersed and held is applied to the interfacial surfaces of the leads 76 and bumps 80 and then hardened.
In recent years, a flip-chip method is also used. In this method, as seen from FIG. 9, leads 76 are formed on the surface of a carrier film 82, and semiconductor chips 78 that are set upside down are caused to approach the leads 76 from above, and boding is performed on the leads and bumps.
However, even in this flip-chip method, there are problems. When achieving a finer pitch, it is likely that more defective products are produced, thus causing yield drop. A detailed investigation of such defective products done by the inventor found the causes of such defective bonding. When the lead 76 contacts a position that is away from the center of the corresponding bump 80, the application of pressure in this state causes the lead 76 to slip on the upper surface of the bump 80 as shown in FIG. 10. As a result, the deviation S increases, and the lead 76 falls from the upper surface of the bump 80.